The Singer/Friden EC-1116 is, feature-wise,
top of the line calculator in the 111x-line of machines designed and built
by Hitachi for Singer/Friden. The 111x-line of machines include
the EC-1112, a first-generation
all-transistor machine that began the line. Later, the second generation
EC-1113 hit the market
utilizing Hitachi's first-generation MOS (Metal Oxide Semiconductor)
small-scale integrated circuits. Shortly thereafter, improvements in
MOS technology allowed somewhat higher levels of integration, through
the use of the HD-3100-series of MOS IC's, especially designed by
Hitachi for electronic calculator applications, used in the
third generation 111x-series calculators, which included the
EC-1114,
EC-1115, and lastly, the
EC-1116. Of the two, the 1116 most closely resembles the EC-1114, with a very
similar keyboard layout, and virtually identical cabinet and internal
structure. The fourth generation in the 111x-series included the
first of early large-scale MOS integrated circuits. These machines,
which included the
EC-1117 and
EC-1118,
dramatically decreased the number of integrated circuits necessary for
a fully-featured calculator. Lastly even higher levels of integration
in the
EC-1117A
made up the last of the series. The 1116 topped all of the machines in
the series in terms of features, with two full-function memory registers,
one-key square root, automatic accumulation modes, constant for multiplication
and division, round-off mode, and a full sixteen digits of capacity.
The price for such functionality was fairly high, with the 1116 selling
for $1,195 in early '71, which was probably somewhat discounted from its
initial introduction price. It appears that the 1116 was introduced sometime
in the early part of 1970, and was actively marketed through mid-1973.

Front Cover of the Operating Instructions for the 1116

The 1116, like all of the other
Singer/Friden 111x-series calculators, was designed and manufactured by
Japanese industrial giant, Hitachi Ltd. Hitachi badged the machines with
Singer/Friden logos and color schemes for distribution by Singer/Friden, through
an OEM agreement. Hitachi sold similar calculators with their own
branding in Europe, but because of the OEM agreement with Singer/Friden in
the US, the Hitachi-branded calculators were not marketed in North America.

The 1116 uses the same general
design as the less-capable EC-1114 and EC-1115, utilizing Hitachi-made
second-generation HD-31xx-series small and medium-scale PMOS integrated
circuits, packaged in ceramic dual-inline packages. A total of 78 IC's
and 46 transistors make up the logic of the machine, with most of the IC's
containing of a few logic gates or flip-flops. A sprinkling of medium-scale
devices are also used in the machine. A number of Hitachi HD3109
shift register chips (each containing a 60-bit shift register and two
four-bit shift registers) combine to form the working and memory registers
of the machine. An HD3112 bit-serial Binary-Coded Decimal adder also takes advantage of
higher-levels of integration to form the foundation of the machines
arithmetic logic unit.
The 1116, along with the 1114 and 1115, are somewhat
unique for their time in that they utilize a completely solid-state design.
Calculators from other manufacturers of the time, such as Canon, Sony, Wang,
and Casio, used magnetostrictive acoustic delay lines or magnetic core memory
for calculator data storage elements, both of which were complex and expensive.
Hitachi's use of integrated circuit devices for register storage began the trend
towards elimination of these somewhat exotic data storage methods in favor
of higher-levels of integrated circuit technology.

Friden 1116 Internal View

Functionally, the 1116 is quite capable
for its time, as far as a business desktop calculator in its price range
goes. The calculator provides a full sixteen digits of capacity, with
fixed decimal point settings from zero through twelve digits behind the
decimal point, making the machine useful for just about any application
from banking to engineering. Two accumulating memory registers with
automatic summation modes make the calculator especially useful for
business and statistical calculations. The machine's automatic one-key
square root function is useful for engineering, statistical, and general
mathematics.

The 1116 is quite easy to operate, with
familiar keyboard controls, and a generously-sized keyboard with keys that
operate smoothly and quietly. The keyboard uses magnetically actuated
reed switches, making the keyboard very reliable. The keyboard bezel is
a beefy cast-metal structure, with a painted panel and chrome accents.
The keycaps are made of a hard plastic, with moulded-in nomenclature to
prevent the keycap legends from wearing off. A smoked plastic cover fits
over the keyboard and display area to serve as a dust cover.

The keyboard is grouped into three sections. The left-most section
contains the clearing-related functions, with the [T1] and [T2] keys
recalling memory register 1 and 2 to the display, then clearing the memory
register. The [CE] key clears the input register, allowing incorrect
entries to be cleared without affecting any math operation in progress.
The larger [C] key clears the calculator working registers, but leaves
the memory registers intact. The center group of keys makes up the standard
numeric keypad. The right-most group of keys provide controls for the
math operations of the machine. The usual [+=] and [-=] keys provide
for adding machine-like addition and subtraction. The [X] and [÷] keys
operate as expected, entering the first number of a multiplication or
division operation, and preparing the machine for entry of the second number.
Pressing the [+=] key finishes off a multiplication or division operation,
calculating and displaying the result. The calculator is capable of chain
operations, allowing an operation such as "3 X 5 X 7" to be performed
by simply pressing [3], followed by [X], followed by [5], followed by [X],
followed by [7], then pressing the [+=] key to display the final result
of 105.

Detailed View of Friden EC-1116 Keyboard Controls

The [R] key swaps the content of the two working registers of the calculator.
This is useful for performing reciprocal division. For example,
entering [3], [&divide], [1], [R], [+=] will provide the result of
"00000000000000.33" with the decimal point selection at 2.
The [√] key calculates the square root of the number currently
in the display. The [M1+] and [M1-] keys add or subtract the content
of the display to/from memory register 1. Likewise, [M2+] and [M2-]
perform the same operations on memory register 2. The [S1] and [S2]
keys recall the content of memory register 1 or 2 to the display, leaving
the memory register intact. The push-on/push-off [K] key activates the
constant function, retaining the first number in multiplication and
division problems for repeated use. Another push-on/push off key, [Σ]
enables automatic accumulation of products or quotients in memory register 1
when depressed.

A large rotary knob located in the lower left corner of the keyboard panel
is used to set the fixed decimal point location, anywhere from zero to
twelve digits behind the decimal point. The 1116 is a fixed decimal output,
floating decimal input machine. It is possible for the user to enter numbers
with more than the number of digits behind the decimal point indicated by
the decimal point selection knob. The calculator will discard or round off
any entra digits, depending on the setting of the "R/O" (Round Off) slide
switch, which is located above the numeric keypad. Another slide switch,
with two positions labeled "OFF" and "ΣMD" controls the accumulation
of multiplicands and dividends in memory register number 2.
A push-on/push off switch with a bright red button controls the power to
the 1116. At the upper right corner of the keyboard is a slider that positions
a series of orange pointers which group the numbers on the display in
groups of three for easier reading of large numbers.

Two indicators labeled "M1" and "M2" at the right
end of the display indicate when the corresponding memory register has
non-zero content. Another indiciator in this area lights to show that
the number in the display is negative. At the left end of the display,
two more indicators provide status of the machine with regard to
overflow conditions. One indicator, labeled "UDF" lights to indicate
that the calculation just completed resulted in an answer that has more
than 16 significant digits. In this case, the result in the display
is accurate to sixteen places, but any additional digits are lost.
The manual calls this indication an underflow condition, which seems rather
counter-intuitive, as such a condition is usually called an overflow.
A second indicator, labeled "DS", for "Decimal Shift", lights to indicate
that the whole number portion of the displayed result is larger than 16
minus the value set on the decimal point position selector. Why
the designers opted for such a complex overflow indication scheme is
a mystery.

The Circuit Boards of the 1116

Internally, the 1116 is built on virtually the same chassis as the 1113 and
1114 calculators. The moulded plastic cabinetry parts are interchangeable
between the three machines, and the internal chassis is very similar.
The 1116 uses a total of four plug-in circuit boards for its logic.
A fifth circuit board provides power supply regulation. The logic boards
plug into a hand-wired backplane that provides the interconnections
between the boards. The circuit boards are made from bakelite, and have
copper traces on both sides of the board, with soldered, plated through
holes providing connections between each side of the circuit board. The
edge connector fingers on the circuit boards are gold-plated for reliability.
The logic boards have a metal edge crimped along three sides to act as a
stiffener, and serve as guides for sliding the circuit boards into the
chassis. The chassis is made of stamped sheet metal. The chassis is not
overbuilt, such as those in competitor Sony's calculators, but
it is sufficient to handle the rigors of shipping and office handling
with no problems.

Smoked Plastic Dust Cover

The 1116 has a few quirks, along with
the already strange overflow notification methods. The machine does not
provide any error indication for illegal operations, such as extracting
the sqaure root of a negative number, or division by zero. Performing
the square root of a negative number simply returns a result as if the
argument were positive. Dividing by zero
throws the machine for a real loop (literally), with the machine beginning
a counting sequence, racking up approximately 485 counts per second.
Pressing the [CE] key during the counting will reset the count to zero as long
as the key is held down, but as soon as the key is released, the counting
resumes from zero. The calculator is unresponsive to all other keys on the
keyboard, except the [CE] and [C] key. Pressing [c] ends the chaos, restoring
the machine to normal operation.

The 1116 has an odd connector located
under the keyboard assembly which isn't present on the 1114 or 1115. Up
until recently, the purpose of this connector wasn't known. As it turns out,
The connector is for an add-on peripheral device called an item counter.
The item-counter is a side-car device that attaches to the right hand side
of the calculator, that has a small pigtail connector that plugs into
the connector under the keyboard of the 1116. The item counter has a three
digit electro-mechanical counter that advances upon the depression of the
[+=] or [-=] keys on the keyboard. A manual pushbutton on the item counter
clears the three digit counter to zero when depressed. A small access hole
exists in the cabinetry of the 1116 to allow the pigtail wire access to the
inside of the 1116. This device is useful in helping perform average,
standard deviation, and other statistical calculations with the 1116 calculator.
It is not known at this time what this option cost. It was designed to be
field installed by a Singer/Friden service technician.

The 1116 performs at about average
speed for machines of this era. Complex square root operations can take
up to 1.25 seconds to complete, with the Nixie tubes madly flickering
during the process. Dividing 9999999999999999 by 1 (with decimal point
location set at 0) takes just about 1 second. Multiplication of 99999999 by
itself takes about 3/4 second. The "UDF" indicator doubles as a busy
indication, and lights during the time the calculator is busy generating the
result. It is not clear if this behavior is designed in, or simply an artifact
of the way the machine's logic operates. Addition and subtraction, both in the working registers and to
the memory registers, is nearly instantaneous, with only a quick flicker
of the Nixies and UDF indicator showing the operation occurring.